The present disclosure relates to a static eliminator and an image forming apparatus that includes such a static eliminator, and more particularly relates to a static eliminator that includes a light source and a light guide member which guides light from the light source so as to emit the light toward an image carrying member and to an image forming apparatus that includes such a static eliminator.
In an image forming apparatus, a charging portion, an exposure portion, a development portion, a transfer portion, a cleaning portion, a static eliminator and the like are provided around an image carrying member. The charging portion uniformly charges the surface of the image carrying member, then the exposure portion performs exposure so as to form an electrostatic latent image on the surface of the image carrying member and furthermore the electrostatic latent image is developed by the development portion. Thereafter, a toner image which is developed is transferred onto a recording medium by the transfer portion, and the recording medium is transported to a fixing portion where the recording medium is fixed and is then ejected to the outside of the apparatus. The toner which is left on the image carrying member at the time of the transfer is removed by the cleaning portion. After the transfer, the static eliminator eliminates charge left on the image carrying member, and the image carrying member is charged again by the charging portion. The residual charge is eliminated before the charging, and thereafter it is possible to uniformly charge the surface of the image carrying member. For the static elimination on the residual charge, the static elimination using light or the like is used.
For example, conventionally, a static eliminator is known that includes an LED lamp (light source), a light entrance portion which light from the LED lamp is made to enter and a rod-shaped light guide (light guide member) which is extended along the axial direction of a photosensitive drum. On a part on the side opposite to the photosensitive drum of the light guide, a reflection portion for reflecting the light from the LED lamp is formed. The light that has entered the light guide travels within the light guide while being diffused, is reflected off the reflection portion to the side of the photosensitive drum and is emitted toward the photosensitive drum.
Incidentally, in the conventional static eliminator described above, the amount of light which is emitted from around the end surface (hereinafter referred to as the one end surface) of the light guide on the side of the LED lamp is larger than the amount of light which is emitted from the other portions of the light guide. It can be considered that the reason why the amount of light which is emitted from around the one end surface of the light guide is larger than the amount of light which is emitted from the other portions of the light guide is the following reason. Specifically, that is because when highly intense and directional light emitted from the LED lamp reaches the reflection portion without being scattered (diffused) on, for example, the surface of the light guide, and is reflected off the reflection portion to the side of the photosensitive drum, the relatively highly intense and directional light reaches the photosensitive drum.
A structure is known in which a large number of minute prisms are formed on the one end surface of the light guide member such that light entering from the one end surface is diffused.